U.S. Pat. No. 5,205,666 of Hollis discloses a trailer hitch of the ball and socket type wherein the socket is formed by a pair of opposed concave socket jaws that pivot between open and closed positions. In their closed position, the jaws align within the outer dimensions of a jaw locking bail, which pivots from an elevated retracted position to a forward, horizontal jaw-locking position. In its forward, locked position, the side walls of the bail completely enclose and engage the forward concave ends of the jaws, preventing the jaws from pivoting outwardly to their open, unlocked position. A drawback of the trailer hitch of Hollis is that it requires the jaw locking bail to be manually pivoted in order to lock the jaws in their closed position.
U.S. Pat. No. 4,042,256 of Lepp discloses a similar ball and socket type trailer hitch utilizing a pair of concave locking jaws and a closure lever that pivots over the locking jaws in their closed position and prevents them from pivoting outwardly to their open position. U.S. Pat. No. 3,046,038 of Hollis employs a similar concept.
The '266 patent, '256 patent, and '038 patent all have the common feature of an outer locking mechanism that secures the jaws in their closed position by enclosing the jaws from the outer sides of the jaws. There is a disadvantage in this approach in that it utilizes a "manually" operated locking mechanism, which can require more than one person to secure the trailer hitch to a towing vehicle.